Tips for '06 Rubicon axles into a '01 TJ

[scherf68]

so do I need to change it out? send me a quote for pv through pm. Thanks

[waynehartwig]

I have not changed out the proportional valve and don't seem to have any problems. What should I expect or should be experiencing with discs in the rear now?

The proportioning valve only proportions the fluid, and stops fluid going to the rear, let's say, when a line breaks or is cut (for those of you with crazy ex wifes) - rather than losing all of your fluid each time you hit the brakes.

If you remove the rubber o ring, like others like to do, defeats this safety feature! and applies half of the fluid to the rear, and half to the front.

Since drum brakes have a smaller bore than a caliper does, you simply don't have enough fluid going back there. Replacing it with a valve from a 4 wheel disc vehicle, like a ZJ for example, will actually give you better braking performance. BTW, performance does not necessarily mean stopping power....

[scherf68]

I have not changed out the proportional valve and don't seem to have any problems. What should I expect or should be experiencing with discs in the rear now?

[waynehartwig]

I own AllJeep.com, and do several axle swaps each month. The most popular are Ford 8.8's and D44's put into TJ/ZJ/YJ/XJ's; in either my shop, or shipped to their respective home.

I registered just to chime in here. Most of you probably have no idea who I am, and some of you might think I have no idea what I'm talking about and will wish I just went away. Some of you will appreciate my experience, knowledge, and willingness to share it with you.

Swapping in D44 axles, front and rear, into a TJ with D30/35 combination is completely bolt in, other than the front driveline being too long and the possibilty of having the wrong u joints. ZJ's have no issues with driveline lengths.

The front D30 knuckles out (brakes, steering, etc) will bolt right up to a Rubicon D44.

The rear M35 (and even CHY 8.25" for you XJ guys) brakes (backing plate, etc) will bolt right up to any newer version D44. CHY 9.25" as well. The brake offset on these axles are the same, regardless if they are disc or drum. The stock TJ e-brake cables will work, with $5 worth of adaption parts; basically you loop the end and use a cable clamp.

In a drum brake TJ, the master cylinder and proportioning valve will need to be changed - yes, they are different! There are modifications that you can make to increase their usability, but you are also disabling their built in safety features. The drum brake master cylinder is different from a disc brake master cylinder, as they do have a check ball in them to keep fluid at the wheel cylinder. If this is used on disc brakes, it will cause them to drag and etc. With the correct parts, you will not need an adjustable proportioning valve.

The Rubicon D44 axles do not use D30, or M35 axle tubes! This is a nasty rumor that is completely false. If you don't believe me, the next time you have all four axles on your garage floor, get out the measuring tools and check it for yourself! The front D44 is a true D44, from inner knuckle (not including the knuckles - inner knuckles out are special for Jeep, not even true D30) to inner knuckle, includes the axle tubes, pumpkin and the pumpkin contents. The rear D44 is a true D44 all the way through. Both pumpkins have been machined differently to accept a different style of carrier than standard D44's. However, a standard D44 carrier will work in a Rubicon D44, but not vice versa.

I welcome all questions, and will answer them all. info@alljeep.com I will also sell you any and all parts you need to make this work, even complete axle assemblies custom built. I will also sell you another adjustable proportioning valve at cost if you seriously think it will help you, TJeeper. I also don't hide behind aliases (absolutley no offense to those that do use aliases for whatever reason), and use this same user name EVERYWHERE I register to. Ebay, PayPal, other forums, etc. So if you see this username elsewhere, chances are very good it is me. If you hear the name elsewhere, it is most likely me.

Anyway, flame on!

[TJeeper]

They may be using the same guage cluster in all the TJ's, regardless of them having ABS or not. Fewer line items to keep track of = lower cost.

They also used them in the later XJs, which is what the full time 4WD icon is for.

[JpPassenger]

You are overthinking this.

Yeah, You aren't the first to level that accusation, and you surely won't be the last.

I do appreciate your tips.
Thanks,
Greg

[Drewminator]

They may be using the same guage cluster in all the TJ's, regardless of them having ABS or not. Fewer line items to keep track of = lower cost.

Oh, got it. Thanks for the information MR. goodtimes

[goodtimes]

That’s odd. Wonder why they would put an icon on the dashboard if the functionality doesn’t exist. Oh well, thanks for pointing that out.

They may be using the same guage cluster in all the TJ's, regardless of them having ABS or not. Fewer line items to keep track of = lower cost.

[Drewminator]

There is a full time 4WD icon on my dash, does that mean my 231 has a full time mode?

That’s odd. Wonder why they would put an icon on the dashboard if the functionality doesn’t exist. Oh well, thanks for pointing that out.

[TJeeper]

Are you sure there isnt ABS on the 06 Rubicon, because there is an ABS icon on my dashboard that said ABS?

There is a full time 4WD icon on my dash, does that mean my 231 has a full time mode?

[Drewminator]

No ABS on the '06 Rubicon's, either. Since we had the 30" wheel package with the D44, we didn't have ABS on our '01 either. But it is something to consider with the swap.

It seems to me that the discs in the rear are more powerfull than the drums were, so it's easier to lock them up now. My wife locked them up coming down a fast wash a couple weeks ago.

I will be the first to admit I don't know the answer, and am happy to hear from those with more experience. I believe the area of the disc piston is greater than the area of the slave cylinder pistons on the previous drum brakes. So the same psi will create more force across the larger area (and the brake pedal does requires more travel, corresponding to more fluid volume needed to move the piston.) I'm not certain how a proportioning valve helps after the initial application.

Are you sure there isnt ABS on the 06 Rubicon, because there is an ABS icon on my dashboard that said ABS?

[TJeeper]

My brake guy was the first to point this out: a MC for discs/drum would have different piston sizes than a MC for a disc/disc system.

You are overthinking this. The MC is the same for all TJs, regardless of year or rear brakes. Also the same as ZJs and newer XJs.

[JpPassenger]

I am not sure what you mean by changing the MC to solve your problem. It won't, and if you think about it, it doesn't even make sense. All you need to do is reduce the pressure to the rears.

I checked my factory manual and confirmed my '01 Master Cylynder has a primary circuit for the front brakes, and a secondary circuit for the rear. This redundancy is pretty common for all modern vehicles.

My brake guy was the first to point this out: a MC for discs/drum would have different piston sizes than a MC for a disc/disc system.

I have a pretty good working knowlege of hydraulics, and it does make sense.

Both pistons are on a common shaft, so they have the same stroke, so the bore size differs. If the drum circuit would require more pressure to apply the brakes than a disc, the bore size would be larger for the drums, supplying more fluid volume, which translates into more pressure. Of course, the caliper or slave cylinder sizes factor into all of this, but I don't have anything to disassemble and measure to do the math.

The real question: is there a difference between MCs or PV for disc/drum systems versus disc/disc systems. Of course they look the same, but a millimeter difference in bore diameter is all that's required.

I have no doubt that the adjustable PV will work, however I'd preffer to fix it with stock parts than special order stuff.

[TJeeper]

or the proper master cylinder for the rear disks.

I am not sure what you mean by changing the MC to solve your problem. It won't, and if you think about it, it doesn't even make sense. All you need to do is reduce the pressure to the rears.

[JpPassenger]

That's a pretty good writeup, Patrick. Thanks for sharing it.

I've had a few more people pointing out that an adjustable valve is needed, or the proper master cylinder for the rear disks. So I'll strike my previous "pretty confident" statement about a rubicon PV.

Thanks for the help.